A known on-demand type of ink-jet printing method forms an image from ink drops on recording paper by discharging ink drops from a nozzle according to image signals. The primary on-demand type ink-jet recording methods are the heater element type and the piezo element type. The heater element type is configured to generate air bubbles inside the ink by energizing heater elements in the ink fluid channel, so that the ink that is pushed by the air bubbles is discharged from a nozzle. The piezo element type is configured so that ink that is present in an ink chamber is discharged from a nozzle utilizing the deformation of a piezo element.
A piezo element is an element that converts voltage into force. When an electrical field is applied to this piezo element, tension or shearing deformation is caused. As a representative piezo element, lead zirconium titanate can be used.
A known configuration of an ink-jet head uses a nozzle substrate that is formed from piezoelectric materials. In this ink-jet head, electrodes are formed on both sides of the nozzle substrate surrounding a nozzle. The ink flows in between the nozzle substrate and a substrate that supports the nozzle substrate. The ink forms a meniscus inside of the nozzle. A drive waveform that oscillates piezo elements is applied to electrodes on the nozzle substrate. By the piezo elements oscillating, supersonic oscillation is generated inside of the nozzle, and the ink inside the meniscus is discharged. The ink-jet head is configured so that, when the piezo elements on the nozzle substrate are excited, the oscillation energy is concentrated in the direction from the peripheral parts of the ink droplet discharge opening to the center. The ink drop is discharged in a direction that is perpendicular to the ink surface.
It is difficult to precisely and cheaply form multiple nozzles on piezo elements, which are ceramic. Formation of the nozzles on piezo elements requires expensive processing costs.